Chiral SiO2 and Ag@SiO2 Materials Templated by Complexes Consisting of Comblike Polyethyleneimine and Tartaric Acid

A facile avenue to fabricate micrometer‐sized chiral (L ‐, D ‐) and meso‐like (dl ‐) SiO₂ materials with unique structures by using crystalline complexes (cPEI/tart), composed of comblike polyethyleneimine (cPEI) and L ‐, D ‐, or dl ‐tartaric acid, respectively, as catalytic templates is reported. Interestingly, both chiral crystalline complexes appeared as regularly left‐ and right‐twisted bundle structures about 10 μm in length and about 5 μm in diameter, whereas the dl ‐form occurred as circular structures with about 10 μm diameter. Subsequently, SiO₂@cPEI/tart hybrids with high silica content (>55.0 wt %) were prepared by stirring a mixture containing tetramethoxysilane (TMOS) and the aggregates of the crystalline complexes in water. The chiral SiO₂ hybrids and calcined chiral SiO₂ showed very strong CD signals and a nanofiber‐based morphology on their surface, whereas dl ‐SiO₂ showed no CD activity and a nanosheet‐packed disklike shape. Furthermore, metallic silver nanoparticles (Ag NPs) were encapsulated in each silica hybrid to obtain chiral (D and L forms) and meso‐like (dl form) Ag@SiO₂ composites. Also, the reaction between L ‐cysteine (Lcys) and these Ag@SiO₂ composites was preliminarily investigated. Only chiral L ‐ and D ‐Ag@SiO₂ composites promoted the reaction between Lcys and Ag NPs to produce a molecular Ag–Lcys]_n complex with remarkable exciton chirality, whereas the reaction hardly occurred in the case of meso‐like (dl ‐) Ag@SiO₂ composite.